Published on: March 2, 2014
by Hannah Devlin for Wisconsin Gazette:
Physical exercise is as important in staving off dementia as keeping your mind active, scientists have said.
Taking a brisk walk three or four times a week can effectively “grow back your brain,” helping to reverse early signs of neurodegeneration and improve performance on memory tests, research has found.
Speaking at the American Association for the Advancement of Science annual conference in Chicago, Kirk Erickson, a psychologist at the University of Pittsburgh, rejected the idea of an inexorable descent into Alzheimer’s disease. “The brain and cognitive function of older individuals remain highly plastic,” he said. “It’s not this inevitable decline that we thought it was.”
In a study involving 120 people aged 60 to 80, half of the participants took part in brisk walking sessions for 30–45 minutes, three to four times a week. The other half spent the same amount of time doing light stretching exercises.
The participants were given cognitive tests and an MRI scan at the beginning and end of the 12-month study.
In the exercising group, the brain scan revealed that the hippocampus region of the brain, which is crucial for memory, had increased in volume by about 2 percent. The pre-frontal cortex, an area involved in decision-making and social behavior, grew by a similar amount. By contrast, in the control group those brain regions shrank by about 1.5 percent, in line with the annual decline in brain volume seen in the elderly.
A reduction in the volume of the hippocampus can be a precursor to Alzheimer’s disease and other forms of dementia. “We were able to increase the size of these areas that had typically deteriorated,” Erickson said. “It’s growing back your brain.”
Exercising also appeared to improve performance on memory tasks and problem-solving. Some of the participants said that, subjectively, they felt sharper. A report released last year showed one in three older adults dies with Alzheimer’s disease and other forms of dementia. Even as deaths from heart disease and stroke have declined, deaths from Alzheimer’s and other forms of dementia increased 68 percent from 2000 to 2010, according to the report from the Alzheimer’s Association.
It’s unclear how exercise improves brain function, but one possibility is that it increases blood flow, which in turn helps to create capillaries. That gives existing neurons a better supply of oxygen and energy. Another possibility is that exercising enhances the activity of genes that trigger the growth of new connections between neurons.
Erickson said that any form of exercise, including walking, swimming or playing tennis, could be helpful and that these activities could have a stronger protection than mental activities such as doing a crossword or a Sudoku puzzle.
“Quite often people are misled into thinking we need lots of exercise to see positive effects. But with moderate exercise we are seeing enormous benefits,” he said. “As we get older we experience cognitive decline. Most cognitive functions decline — memory and some language functions. There has been growing interest in ways to prevent decline from happening, and delay losses and even reversing some losses that have already taken place. There is a great proportion of the population who are not 65 years and older, and so this is cause for some alarm. That is really why physical activity is so important.
“Results from these studies suggest that the brain and cognitive function of older individuals remain highly plastic. It’s not this inevitable decline that we thought it was. We don’t have a good understanding of how long the effect persists.”
A study reported in December also found that living healthily could cut the risk of developing dementia by about 60 per cent. Scientists at Cardiff University in Wales have been following 2,235 men since 1979, looking at the link between disease and regular exercise, eating fruit and vegetables, staying slim, light drinking and not smoking. Researchers said that only 1 percent of the population had all five healthy habits, with numbers unchanged over three decades. Five percent had four.
People who followed four out of the five healthy habits were 60 per cent less likely to suffer from cognitive decline or dementia, with exercise accounting for a significant chunk of the effect. So far 219 of the men have shown signs of cognitive decline and 79 have dementia.
If half the men in the study had taken up one extra healthy habit 30 years ago, there would have been 13 per cent fewer cases of dementia today, with a 12 per cent drop in diabetes, a 6 per cent fall in heart disease and 5 per cent fewer deaths, the research team said.
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